Put the cornstarch in a cup. Add the remaining 1 tablespoon water, stirring to dissolve. Stir into the soup. Increase the heat to medium high and bring to a boil. Boil for 1 to 2 minutes, or until thickened, stirring occasionally.

Cook's Tip

Toasted sesame oil provides the authentic Asian flavor in this recipe. Also known as Asian sesame oil, it is darker and has a stronger flavor than regular sesame oil, which is virtually flavorless.